This invention relates to a method and apparatus for manufacturing a tubular filter from a non-woven fabric web, and the resulting product.
Filters having non-woven fabric structures are presently utilized for filtering materials such as paint and various chemicals. Such filters are especially useful for filtering enamels to remove gel particles or unmilled paint particles therefrom.
The term "non-woven fabric web" as herein employed is intended to mean a needled felt web formed of relatively short (up to several inches in length) mechanically interlocked fibers or strands having various relative orientations.
Commonly utilized filters of the aforementioned type comprise a cylindrical perforated core of resin impregnated paper wire mesh, or perforated steel upon which has been deposited a non-woven fabric web. A cylindrical wire tube or tubes to which a vacuum is applied, is immersed in a water slurry of fibers and water emulsified resins (as a binder). The wire tubes are slowly turned while in the slurry and a deposit of fiber and binder is formed. The formed fibrous cylinder is next transferred to an oven to drive off the water and cure the resin binder.
Disadvantages of the aforementioned prior art process and resulting filter are (i) a tremendous amount of water has to be driven off in the drying process so the resin can be cured, requiring a great deal of energy; (ii) the process is relatively "messy", and unsuitable for use in manufacturing small quantities of special purpose filters; and (iii) the fibers of the resulting filter are not randomly oriented, as may be desirable in certain applications, but due to the rotation of the fiberglass core are oriented in a generally annular direction.
In addition, special prior treatments to the felts such as singeing, glazing, calendaring, and fabric scrim reinforcement cannot be performed in conjunction with said prior art process.
Accordingly, an object of the present invention is to provide a tubular non-woven fabric filter which overcomes the aforementioned disadvantages, and a process and apparatus for manufacturing the same.